[Ethereum] the first ever ERC20 token creation transaction

I do not think there are dedicated tools for that. On high level, you could use e.g. MyEtherWallet, interface the contract address with a generic ERC20 ABI and try it out.

On lower level you could try the following approach: An ERC20 implements the following functions

totalSupply()
balanceOf(address)
allowance(address,address)
transfer(address,uint256)
approve(address,uint256)
transferFrom(address,address,uint256)

You can use some tool to calculate the function identifier which is the first 4 bytes of the keccak hash of the function identifier as pasted above. These identifiers are thus:

18160ddd -> totalSupply()
70a08231 -> balanceOf(address)
dd62ed3e -> allowance(address,address)
a9059cbb -> transfer(address,uint256)
095ea7b3 -> approve(address,uint256)
23b872dd -> transferFrom(address,address,uint256)

You can now take some token creating transaction (e.g. this on here creating the Tend token) and check if the function identifiers are present in the bytecode (input data of the contract creating transaction). This is not guaranteed to really be an ERC20 (because the 4 bytes could pop up somewhere randomly) but it is probably a good way to be relatively sure by just looking at the bytecode (which nobody can hide).

It knows because:

1. The contracts implement the standard ERC20 interface
2. The address is calling the transfer(address to, uint amount) function on the ERC20 contract
3. The contract logs the standard ERC20 event Transfer(address to, uint amount)